"But I am happy to talk to people looking for advice on foreign policy issues," said Burt, a managing director of McLarty Associates, a Washington-based consulting firm co-founded by former President Bill Clinton's White House chief of staff and counselor Thomas "Mack" McLarty. Burt said he also would be willing to offer foreign policy advice to Hillary Clinton, the presumptive Democratic presidential nominee, if she asked for such advice, though he added, "She's not going to."Burt is also chairman of Global Zero, an independent group devoted to ridding the world of nuclear weapons. Trump told The New York Times in April that he was not sure it would be "a bad thing" for the United States if Japan had nuclear weapons, and has said the same about South Korea and Saudi Arabia.

Burt said the main theme he talked about to Trump was the need for the United States to pursue a "more realist foreign policy," in which the United States would avoid seeking "regime change" abroad, and instead make protecting the United States and its interests the main policy goal. Trump, who became the Republican's presumptive nominee last month after the last of his challengers dropped from the party's race, articulated this theme again in a campaign speech late on Tuesday, as he claimed victory in the last Republican nominating contests.

Under Reagan, Burt headed the State Department's Bureau of Political-Military Affairs and then its European and Canadian Affairs bureau and served as U.S. ambassador to Germany from 1985 to 1989.

Some of Burt's contemporaries from the administrations of Presidents Reagan, George H.W. Bush and George W. Bush, have publicly denounced Trump's foreign policy views or remained mute.

Earlier this year, Trump met with a group of 11 foreign policy advisers, headed by Republican Senator Jeff Sessions of Alabama, one of Trump's most outspoken supporters.

Reuters sought comment on the recent activities of Trump's foreign policy team from several of its members and from a campaign spokeswoman. Most declined to comment, and the campaign did not immediately reply to a request for comment.

One campaign team member, who asked for anonymity because he is not authorized to comment publicly, said that while the team had held several discussions since Trump's speech, the candidate remains his own most important foreign policy adviser.

(Reporting By Mark Hosenball; Editing by John Walcott and Leslie Adler)